Current semiconductor devices typically include a die, a substrate, one or more metallization layers, I/O pins or balls, a heat spreader and optionally a heat sink. The die contains the active circuitry of the device. The die is typically mounted on the substrate or in a cavity within the substrate. One or more of the metallization layers include pads called bond-fingers that are used to interconnect the metallization layers to die-pads of the die. The die pads are, in turn, interconnected with the active circuitry of the die. The metallization layers route electrical connections within the substrate from the die to the I/O pins or balls.
The die-pads may be electrically coupled to the bond-fingers using conventional wire bonding, by connecting the pads to the bond-fingers by conductive wires. Alternatively, the die can be mounted with its active surface, facing the substrate. Die pads extend from the active surface, and may connect to the bond-fingers using electrically conductive bumps extending from the die. As the active surface faces down, such semiconductor devices are often referred to as “flip chip” packages.
In modern semiconductor packages, the continued push for higher performance and smaller size leads to higher operating frequencies and increased package density (more transistors). However, in operation the circuitry on such a die consumes an appreciable amount of electrical energy. This energy invariably creates heat that must be removed from the package. Conventional heat spreaders and heat sinks may be used to dissipate the heat generated by the die. However, as the majority of the heat is generated in the die, the relative distribution of thermal energy within the chip package is often quite uneven.
More recently, in an effort to include more transistors in a single package, multiple dies may be packaged in a single semiconductor device. For example, dies may be stacked one upon another with each die interconnected with the substrate. To this end, U.S. Pat. No. 7,361,986 discloses semiconductor device with two stacked dies, a first die mounted in a flip-chip configuration with another mounted atop the first die, and wire bonded to the substrate.
As the geometry of multiple dies become more complex, and the number of transistors increases, dissipating heat from the electronic dies becomes an increasing problem.
Accordingly, there is a need for a semiconductor package that assists in the heat dissipation of multiple dies.